Prior shot terminals such as smart phones, digital cameras, video cameras and so on, capture the external image with a lens, and a photoelectric conversion device will convert the image captured by the lens into electrical signal, and then a display device displays the image. Specifically, the lens refracts the external light to the photoelectric conversion device, and then the photoelectric conversion device converts a part of the light into electrical signal to form initial image data the size of which is A*B (A, B are positive numbers greater than zero). Then, partial image data in the initial image data is captured for facilitating display or storage, to obtain new image data the size of which is a*b (a, b are positive numbers greater than zero, a being less than A, b being less than B). Then, the new image data is sent to a displayer for display or to a memory for storage.
When partial image data in the initial image data is captured, the partial image data in the initial image data is identically captured. For example, if the size of the initial image data is 1000*600 and the central point is O1, the new image data the size of which is 500*300 is captured identically while O1 is regarded as the central point, that is to say, the size of viewfinder is 500*300 and the central point O2 of the viewfinder overlaps with the central point O1 of the initial image data. However, in the actual shooting process, users always hope a target to be shot, such as a scene or a person, is located at a particular place (for example, a person is in the middle or at the golden section point). Users need to manually adjust the shooting direction or shooting angle of a shooting terminal so as to enable a target such as a scene or a person to be located at a particular place. The manual operation of users leads to inaccurate shot image data and great errors.